Polymerization of gases



Fe. F. RUTHRUFF Re. 20,931

POLYMERIZATIGN CF GASES Nov. 29, l

Original Filed Aug. 24, 1952 ow olofa'n,

Ole/2m 77 INVENTOR ATTORNEY Ressued Nov. 29, 1938 PATENT GFFICE POLYIKERIZATION F GASE S,

Robert F. Ruthrui, Nutley, N. J., assigner to Standard Oil Company, Chicago, Ill., a corporation of Indiana.

Original No. 2,017,325, dated 0ctober'15, 1935,

Serial No. 630,282, August 24, 1932. Application for reissue 138,0791/2 20 Claims.

hydrogen, etc., are eliminated and the thus concentrated oleiinic gases are polymerized. After the polymerization step, fixed gases undissolved by the liquid polymerization products are elimi- 20u nated by a high pressure separator, and low pressure gases subsequently released from the polymerization products are recycled to the polymerization system and/or to the cracking system.

I have discovered that by carrying out the separation between the scrubbing medium and dissolved gases, and also the separation between liquid polymerization products and dissolved unreacted gases, in a plurality of stages subsequent to an initial high pressure separation and removal of undissolved fixed gases, certain gas fractions of unexpectedly high olefin content may be obtained and may be so combined and recycled as to considerably increase the olefin content of the gas charged-to the polymerization system.

Briefly described, thel operation of my system is as follows:

Considering first the polymerization systemfor example .,(subsequent to the initial high pressure step), first separateA a gas of low olefin content and then one of high olefin content, the first separated gas being eliminated from the system :a and the second recycled. 0n the ,other hand,

oil at elevated pressures, undissolved methane,`

are recycled to the polymerization step. I may,

April 21, 1937, Serial No.

(Cl. 19E-10) I may yuse more than two separation stepsand also I may recycle varying proportions of the gases from the several stages instead of completely eliminating any one stream from the system. v

The number of stages used, the exact pressure maintained ineach, and the composition and disposition of the gas released in each stage (i. e.

whether recycled or eliminated) will, of course, depend on the composition of the unreacted gases leaving the polymerization step, which, in turn, will depend on the composition of the fresh olefin gases fed to the system and on the exact conditions maintained therein.

I may also operate my process in conjunction with a gas cracking step. In this case saturated gases are cracked-at elevated temperatures and relatively low pressures. The resulting low olefin content gas is cooled and scrubbed under higher pressures, the fixed gases are eliminated, the scrubbing oil and dissolved gases are separated stepwise in a plurality of' stages and gases are removed from each stage. The gas separated from each stage is controllably (1) recycled to the cracking step, (2) delivered to the polymerization system, and (3) divided between (1) and (2) in determined proportion so as to establish optimum ultimate yield conditions.

When my polymerization system is operated In conjunction with a gas-cracking system, low olefin content gases separated in one or more of the plurality of gas-product separators following. the h igh pressure separator of the polymerization system are not discarded, b'ut are returned to the gas-cracking step.

Suitable apparatus for carrying out my process is shown diagrammatically in the attached drawing which represents an elevational view thereof, and which fornis part of this'speclfication.

The operation of my process inI detail is as follows: Y

Referring to the drawing and considering first the polymerization system alone. Relatively ccncentrated olefin gases containing over 50% of gaseous olefins enter through line I0 and are compressed by pump II to 50G-3000 pounds per square inch and introduced into the heating coils of heater I2, wherein the gases are heated to '15G-1000" F. Heater I2 may contain preheating and soaking coils in which the reactions are com-` pleted, or it may function solely as a preheateryin which case valve I3 in exit line I4 is closed,I valves I5 and I6 are opened, whereby the polymerization reactions are permitted to complete themselves in soaking chamber I1. In either case, all gases and products are cooled in cooler Il and passed through valve I9 into high pressure separator 20. Separator 241s ordinarilyoperated at full reaction pressure, but a slight reduction of pressure may be made at valve I8 if desired. 'I'he iixed gases which are not susceptible to further.

reaction or even to re-cracking to oleiins are eliminated through 2| and products containing dissolved gases are drawn out through 22, the pressure reduced at valve 2i and said products and gases are introduced into intermediate separator 24. Gases may be removed from separator 24, through valve 25, pump 2l and line 21 for recycling to the polymerization step, or may be wholly or partly vented from the system through valve 28. Liquids and remaining dissolved gases are removed through valve 29 and line Ill, wherein the pressure is further reduced and are introduced into low pressure separator 3l from which essentially gas-free products are withdrawn through 32, while gases may be recycled through 33 or wholly or partly vented from the system through 34. g

As previously stated I may operate my system in conjunction with a gas-cracking system, in fact, I may carry out the entire operation starting with essentially saturated or paraillnic gases.

Referring again to the drawing, if this set-up be used, predominantly saturated eases enter through line 35 and are crackedat temperatures of 1soo175o F. and o Lm 10o lbs. per square inch pressure above atmospheric or thereabouts in heater 36, from which these gases either pass through valve 31, soaking chamber Il and valve 39, or may be passed through valves 4l, by-pass 4I and valve 42. In either case the gases are essentially completely cooled in cooler 43, following which any liquid condensates may be drawn on' through 44 prior to compression of the gases by pump and injection of said compressed gases into scrubber 46. In the scrubber 4l the gases which have an olefin content of not over by volume (and ordinarily of less than 40% olefins by volume) are contacted with a suitable. scrubbing oil whereby oleiinic hydrocarbons (and to a somewhat lesser extent the saturated hydrocarbons hving two or more carbon atoms) are dissolved. Fixed gases, such as hydrogen or methane, are eliminated through 41, cool scrubbing oil being introduced through line 48,` while ally through he t exchangers 58 arid 5| enriched oil is withdrawn through-49 and valve 50, passed through interchanger or heater 5I and introduced into intermediate separator 52. Separator 52 may be equipped with suitable heating means 53 at a low point therein and may kbe provided with cooling means 54 at an upper point therein. Gases driven ofi' in 52 are withdrawn through line 55, while the liquid and still remaining dissolved gases are withdrawn through '55 and valve 51, passed through heat interchanger or heater 5B and enter separator 59 which likewise may be provided with heating means GII and.

cooling means 5I. Gases driven oil' in this separator are removed through line 52, while stripped scrubbing oil. isremoved through valve 53 and line 64 and recv` ed by pump B5, passing optionand nally through a cooler prior to reintroduction into scrubber 45 through line 4I.

The gases in lines 55 and 62 eliminated respectively from separators 52and 59 may be optionally passed through valves 81 and 58 to inlet line I0 oi the previously described polymerization system or through valves 55 and 10 respectively `to the inlet line I5 of the cracking system. i

In the simpler and preferred modification of my process I use two separation steps subsequent to the initial separation of xed gases, both in Y the polymerization system and in the olefin gas concentration system. `In this case essentially all of the gas from the rst separator or separators is passed to the polymerizing system inlet, while essentially all of the gas from the second separator or separators is eliminated from the system or returnedto the gas cracking step, or vice versa.

It will be understood that altho I have shown the use of separation of dissolved gases by stepwise reheatingin the oleiin concentration step and by stepwise pressure reduction in the polymerization product separators, Ido not limit myself to this arrangement but may use. stepwise reheating in either or both systems,. or stepwise :l

pressure reduction in either or both systems. I may, however, use more than two intermediate separators following the high pressure separator 20 or scrubber 46. The distribution of gases from each separator between inlet 35 to the cracking system or inlet ID of the polymerization system will be so determined as to g`ive the optimum concentration of olefin gas entering the polymerization system and will be dependent -upon the composition of the original gas fed to the cracking or polymerization step through line I5 or line III. on the exact conditions.` maintained during the cracking and polymezation steps and on the exact conditions maintained in the scrubber 45 and separator 20 and the separators iollowing thereafter.

Ii my polymerization system be so operated in conjunction with a gas cracking system, instead of eliminating from `the system gases from separators 24 or 3l of the polymerization system `through vents 2l or 34 respectively, any gases from these separators that are not desirable for recycling to the polymerizing s tep through line and/or 52 through valves 14 and 15 respectively and inject said materials by pump 15 through line 11 into the inlet ,Ill to the polymerization heater I2.

I may also operate my polymerization system in conjunction with the oleiin concentration system represented by- 45 to 65 but without the gas cracking system 3`5-44. In this case I may operate on low olen content gases obtained or pr'oduced from any suitable source which are introduced through line 1 and valve 19 into the ixrtake oi' pump 45. In this case, the operation of all other parts of my system is as previously described. It will also be evident that the olen concentration syste'n 45-58 may be operated independently in order to produce a rich olefin gas for any purpose from lean oleiln gas from any source. 4 I

It I operate my polymerization system in conjunction with the cracking systemfand make use of three or more separators in my oleiln concentration system 45-65, then I may under certain circumstancesv make use of only two stages of separation between polymerization products and f 25, 29 and 1I, thereby .eliminating the intermediate separator 24. All other details of operation of my system will remain as previously described.

If I operate my polymerization system in conjunction with the olefin concentration system 45 to 68, but without the gas'cracking system, I may make use of line 8| and valve 82 whereby I may divert gas released from one or more of the separators 24, 3|, etc., back to the olefin concentration step.

Altho as previously stated I do not limit myself to the 'use of only two intermediate separators subsequent to the initial fixed gas separator, I prefer to use only two such separators. I also prefer to select my starting materials and to operate my polymeriz-ation and/or cracking systems and my separators so that an olefinic gas is separated in the first intermediate separator and a loW olefin content gas in the second intermediate separator. advantage that the olefinic gas which is to be recycled to the high pressure polymerization system is in all cases obtained or recovered at the highest possible pressure, whereby considerable operating economies are realized.

It will beunderstood that scrubber 46 and separator 20, 24, 3l, 52, and 59 may be provided with bubble or baille` plates and/ or any other conventional. means for improving scrubbing or separations respectively therein. Whenever the term substantially full reaction pressure is used herein or in the claims hereof with respect to the operating conditions of high pressure sep arator 20, this is to be understood as being subject to the qualification that frequently it is preferable not to operate the said separator at pressures above 2,000 lbs. per square inch since at the temperatures attainable with ordinary vcooling water, separation of phases is frequently not satisfactory at higher pressures than this. In case, therefore, that I make use of reaction pressures of above 2,000 lbs. I may reduce pressure to at least that point by valve Il prior to high-pressure separator 20.

By low olefin content gases, where this term 'is used herein, I refer to gases having olefin contents of less than 50% and ordinarily of more than 20%. By predominatingly saturated gases, such as I may use as charging material for the high temperature gas cracking step, I refer to gases containing 20% or less of gaseous olefins or containing none thereof. By olefinic gases or olefinic gas" I refer to gases having an olefin content of 50% or more and preferably of more than 65% such as may be obtained by the concentration steps described herein or may be obtained from other sources.

The foregoing being av full and complete description of my invention,

I claim:

l'. In a process 'for the polymerization of olefinic gases at temperatures of '150-1000" F. and under pressures of 500-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in at least three stages at progressively lower pressures, separating fixed gases from products in the first stage, eliminating fixed gases from the system, separating olefinic gas from at least one stage subsequent to the first stage and recycling substantially all of said gas directly tothe polymerizationstep, and eliminating the predominatingly saturated gases separated in the other stages lfrom the system.

This type of operation has the added f 2. In a process for the polymerization of oleiinic gases at temperatures of '750-1000 F. and

under pressures of 500-3000 lbs, per sq. in., the

steps of separating fixed gases from products at substantially full reaction pressure and rela` s tively low temperature and eliminating said fixed gases vi'rom the system, separating remaining gases from liquid products in at least two subsequent stages `at progressively' lower pressures, separating olefinic gas from at least one stage and recycling substantially all of said gas direct- 1y to the polymerization step, and eliminating the predominatingly saturated gases separated in the other stages from the system.

3. In a process for the polymerization of olefinic gases at temperatures of 750-1000 F. and under pressures of 500-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in at least three stages at progressively lower pressures, eliminating substantially allgases from the first stage from the system. recycling olefinic gases Afrom at least one stage directly to the polymerization step, subjecting predominatingly saturated gases from at least one stage to cracking at 13001750 F. to obtain additional olefinic gases therefrom, and return-l ing said olefinic gases to the polymerization step.

4. In a process for the polymerization of oleunder pressures of 500-3000 lbs. per sq. in., the

steps of separating liquid products from unreacted gases in three stages wherein the first stage is at substantially full reaction pressure and relatively low temperature and the subsequent stages are at progressively lower pressures, eliminating fixed gases from said first separating stage from the system, recycling olefinic gases from the second separating stage directly to the polymerization step, and 4eliminating predominantly saturated gases from the third separating stage from the system.

5. In a process for the polymerization of oleiinic gases at temperatures of '750-1000 F. and under pressures of 500-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in three stages wherein the first stage is at substantially full reaction pressure andrelatively low temperature and the subsequent stages are at progressively lower pressures, eliminating xed gases from said first stage'from the system, recycling olefinic gases from the second stage directly to the polymerization step, subjecting predominatingly saturated gases from the third separating stage to cracking at13001750 F. to obtain additional olefinic gases therefrom,

.and returning said olefinic gases to the polyarating said liquidproducts. from unreacted gases in at least three stages wherein the first stage is at substantially full reaction pressure and at relatively low temperature and the subsequent stages are at progressively lower pressures, eliminating undissolved fixed gasesfrom the first separating stage from the system, separating dissolved gases from liquid products in at least two subsequent stages, separating oleilnic gas from at least one of said stages, recycling said gas directly to the polymerization step, and separating low olefin content gas from at least one of said stages and returning said gas to the oil scrubber of the olefin concentration step. t

7. In a process for the production of liquid products from predominatingly saturated gases, the steps of cracking said gases at temperatures of 1300-1'750o F., scrubbing cracked gases with oil at elevated pressures, eliminating undissolved gases, separating dissolved gases from scrubbing oil in at least two subsequent stages at progressively lower pressures, recovering olenic gas from at least one of said stages, recycling predominatingly saturated gases from at least one of said stages directly to the gas cracking step, polymerizing aforesaid olenic gas at temperatures of rX50-1000" F. and under pressures of 50G-3000 lbs. per sq. in., separating unreacted gases from liquid products in at least three Astages at progressively lower pressures, eliminating gases separated in the rst stage from the system, recycling olefinic gas separated from at least one stage directly to the polymerization step, and recycling predominatingly saturated gases separated from at least one stage directly to the rst named gas cracking step.

8. In a process yfor the production of liquid products from low olefin content gases, the steps of scrubbing said gases with oil at elevated pressure, eliminating undissolved xed gases, recovering olenic gas in a second separating stage, polymerizing said olefinic gas to liquid products at temperatures of 'TSO-1000 F. and under pressures of 50G-3000 lbs. per sq. in., separating said liquid products from unreacted gases in three products from predominatingly saturated gases,

the steps of cracking said gases at temperatures of i300-1750 F., scrubbing cracked gases with oil at elevated pressures, eliminating undissolved gases, separating dissolved gases from scrubbing I, oil in two stages at progressively lower pressures,

recovering olefinic gas from the rst stage, recycling'predominatingly saturated gases from the second stage directly to the cracking step,l polymerizing aforesaid olenic gas at temperatures of '750-1000" F. and under pressures of 500-3000 l ly to the first-named gas cracking step.

l0. In a process for the polymerization of olefinie gases at temperatures of850" to 1000 F.

and under pressures of 500 to 2000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in at least three stages at progressively lower pressures, separating fixed gases from products in the rst stage, eliminating iixed gases from the system, separating gas relatively rich in olefins from at least one stage subsequent to the irst stage and recycling substantially all of said .gas directly to the `polymerization step, and eliminating the gases low in polymerizable `constituents separated in the other stages from Vthe system.

quent stages at progressively lower pressures,

separating gas relatively rich in olens from at least one stage and recycling substantially all of said gas directly to the polymerization step, and eliminating the gases low in polymerizable constituents separated in the other stagesr from the system.

12. In a process for the polymerization oi. olenic gases at temperatures of '750-1000 F. and under pressures of 500-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in at least three stages at progressively lower pressures, eliminating substantially all gases from the first stage from the systemrecycling gas relatively rich in olens from at least one stage to the polymerization step, subjecting gas low in polymerizable constituents from at least one stage to cracking at 13001750 F. to obtain additional gas relatively rich in olens therefrom, and returning said gas relatively rich in olefins to the polymerization step. 13. In a process for the polymerization of oleilnic gases at temperatures of 750-1000 F. and under pressures of 50o-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in three stages wherein the rst stage is under high super-atmospheric pressure and relatively low temperature and the subsequent stages are at progressively lower pressures, eliminating xed gases from said first separating stage from the system, recycling gas relatively rich in oleflns from the second separating stage to the polymerization step, and eliminating gas low in polymerizable constituents from the third separating stage from the system.

14.-In a process for the polymerization of olenic gases at temperatures of r15G-1000 F. and under pressures of 500-3000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in three stages wherein the rst stage is under high super-atmospheric pressure and relatively low temperature and the subsequent stages are at progressively lower pressures, eliminating fixed gases from said rst stage from the system, recycling gas relatively rich in oleiins from the second stage to the polymerization step, subjecting gas low in polymerizable constituents from the third separating stage to cracking at l 1300-1750 F. to vobtain additional gas relatively rich in olens therefrom, and returning said gas relatively rich in oleiins to the polymerization step.

' 15. In a process for the production of liquid products from low olen content gases, the steps of scrubbing said gases with an oil at elevated pressure, eliminating undissolved gases, separating dissolved gases from the oil in at least two subsequent stages at progressively lower pres- Cil . returning said gas to the oil scrubber of the olefin` sures, recovering gas relatively rich in olenns from `at least one of said stages, polymerizing said gas relatively rich in oleiins to liquid products at temperatures of '15G-1000 F. and under pressures of 500-3000 lbs. per sq. in., separating said liquid products from unreacted gases inat least three stages wherein `the ilrst stage is under high superatmospheric pressure and at relatively low temperature and the subsequent stages are at progressively lower pressures, eliminatingv undissolved xed gases from the iirst separating stage from the system. separating dissolved gases from liquid products in at least two subsequent stages, separating gas relatively rich in olens from at least one o! said stages, recycling said gas tothe polymerization step, a-nd separating low olefin content gas from at least one of said stages and concentration step.

16. In a process for the production o! .liquid products from predominatingly saturated gases, the steps of cracking said gases at temperatures of 1300-1750 F., scrubbing said cracked gases with oil at elevated pressures, eliminating undissolved gases, separating dissolved gases from scrubbing oil in at least two subsequent stages at progressively lower pressures, recovering gas relatively rich in olens from at least one of said stages, recycling predominatinglysaturated gases from at least one of said stages to the gas cracking step, polymerizing aforesaid gas relatively rich in oleflns at temperatures of '15o-1000 F. and

under pressures of 500-3000 lbs. per sq. in., separating unreacted gases from liquid products in at least three stages at progressively lower pressures, eliminating gases separated in the first stage from the system, recycling gas relatively rich in olefins separated from at least one stage to' the 'polymerization step, and 'recycling predominatingly saturated gases separated from at least one stage to the iirst named gas cracking step.

1'?. In a process tor the roduction of liquid products from low oletln contentgases, the steps of scrubbing said gases with oil at elevated pressure, eliminating undissolved ilxed gases, recovering gas relatively rich in oleflns in a second separating stage, polymerizing. said gas relatively rich in olens to liquid products at temperatures of 'Z50-1000 F. and under pressures of 500-3000 lbs.

per sq. in., separating said liquid products from.

unreacted gases in three stages wherein the first stage is under high super-atmospheric pressure and at relatively low temperature and the subsequent stages are at progressively lower pressures,

leliminating xed gases from the rst separation stage from the system. separating gas relatively rich in olens from the second stage, recycling said gas to the polymerization step, separating low olefin content gas from the third stage, and returning said low olen content gas to the oll scrubber of the olefin concentration step.

18. In a process for the production of liquid products from predominatingly saturated gases, the steps of cracking said gases at temperatures of 1300-1750 F., scrubbing cracked gases with oil at elevated pressures, eliminating undissolved gases, separating dissolved gases from scrubbing oil in two stages at progressively lower pressures, recovering gas relatively rich in oleflns from the rst stage, recycling predominatingly saturated gases fromvthe second stage to the cracking step, polymerizing aforesaid gas relatively rich in olens at temperatures of 7504000 F. and under pressures of 500-3000 lbs. per sq. in., separating .unreacted gases from liquid products in three stages wherein the first is under high super-atmospheric pressure and relatively low temperature and subsequent stages are at progressively lower pressures, eliminating xed gases separated in the rst stage from the system, recycling gas relatively rich in olens separated in the second stage to the polymerization step, and recycling gases separated in the third stage to the first named gas cracking step.

19. In a process for the polymerization of oleiinic gases at temperatures of 850 to 1000 F. and under pressures of 500 to 2000 lbs. per sq. in., the steps of separating liquid products from unreacted gases in at least three stages at progressively lower pressures, separating fixed gases from products in the rst stage, eliminating fixed gases from the system, separating gas relatively rich in oleiins from at least 'one stage subsequent to the iirst stage and recycling substantially all of said the gases low in polymerizable constituents separated in the other stages from the system.

20. In a process for the 'polymerization of oleflnic gases at temperatures of 850 to 1000 F. and under pressures of 500 to 2000 lbs. per sq.'in., the steps of separating ilxedgases from products under high super-atmospheric pressure and relatively low temperature and eliminating said iixed gases from the system, separating remaining gases from liquid products in at least two subsequent stages at progressively lower pressures, separating gas relatively rich in olefins from at least one stage and recycling substantially all of said gas to the polymerization step, and eliminating the gases low in polymerizable constituents separated in the other stages from the system.

' ROBERT F. RU'I'HRUFF. 

